Question

Why is colchicine used for preparing karyotypes?

a)Cells become stalled in metaphase with condensed chromosomes because colchicine prevents microtubules from forming.
b)Microtubule polymerization is required for chromosome condensation.
c)Colchicine prevents the breakdown of the nuclear membrane during mitosis so that the chromosomes cannot align on the metaphase plate
d)Colchicine is useful for all of the above reasons.
e)Colchicine binds to chromosomes to aid in condensation during mitosis.

Answer 1

Colchicine is used in karyotyping to halt cells in metaphase by disrupting microtubule formation, leading to highly condensed and visible chromosomes which are essential for identifying chromosomal abnormalities.

Step-by-step explanation:

Colchicine is used for preparing karyotypes because it has the ability to stall cells in metaphase by preventing microtubules from forming. This has a direct impact on the mitotic spindle, which is essential for the segregation of chromosomes during cell division. Because colchicine inhibits the polymerization of microtubules, chromosomes become highly condensed and do not move to the cell poles. This allows for the chromosomes to spread apart and become clearly distinguishable when a cell is placed under pressure and observed under a microscope during the karyotyping process.

By interfering with the spindle apparatus, colchicine effectively halts cell division during metaphase, a stage where chromosomes are most condensed and most clearly visible. This is critical for creating a karyotype, where chromosomes can then be observed and any chromosomal abnormalities can be identified.